public class SecondThread implements Runnable{
    private int i;

    @Override
    public void run() {
        for(; i < 100; i++){
            System.out.println(Thread.currentThread().getName() + " " + i);
        }
    }

    public static void main(String[] args) {
        for(int i = 0; i < 100; i++){
            System.out.println(Thread.currentThread().getName() + " " + i);

            if( i == 20){
                SecondThread st = new SecondThread();
                new Thread(st, "New Thread 1").start();
                new Thread(st, "New Thread 2").start();
            }
        }
    }
}
